Drug testing of biological specimens such as urine, oral fluid, breath, sweat and hair provides an objective means of diagnosing drug use and monitoring subjects in treatment. Traditionally, urine testing has been used, but this technology has limitations. In a series of ongoing studies, a variety of alternative biological fluids and tissues are evaluated for usefulness in monitoring individual patterns of substance abuse. Clinical studies were designed to determine the identity, concentration, time course, dose dependency and variability of drug and metabolite excretion in urine, plasma, oral fluid, sweat, skin, sebum, nails, cord blood, and hair following administration of single and multiple doses of drugs of abuse to human subjects. Each biological specimen appears to be unique and offers a somewhat different pattern of information regarding drug use over time. For example, hair testing offers the possibility of detecting drug use that could have occurred within a period of several months and could be useful in monitoring individuals in long-term treatment and in prevalence studies. In contrast, oral fluid offers a short term measure of drug exposure that may correlate more closely with some drug concentrations in blood and with drug-induced effects. Sweat can be used for monitoring over a period of 1-2 weeks. Oral fluid, hair and sweat testing for drugs of abuse are currently under consideration for federally mandated drug testing programs, and are being employed more commonly in workplace, criminal justice, treatment and military drug testing programs. There may also be disadvantages associated with the use of a particular biological matrix. Basic pharmacological properties such as dose-concentration and concentration-time relationships are evaluated in our research. Overall, each biological matrix shows promise of revealing useful information regarding an individual's drug exposure history. Analysis of drugs in alternative matrices requires development of sensitive, selective and specific chemical methods for the detection and quantification of drugs and metabolites. Analytical procedures are continually evaluated for improving the detection and quantification of parent drug and metabolic products of cocaine, opiates, methamphetamine, cannabinoids and nicotine in blood, plasma, sweat, oral fluid, urine, skin, sebum and hair.